The present invention relates to an electronic-circuit assembly, and more particularly to an electronic asemmbly having a plurality of substrates which are stacked.
An example of such a conventional electronic-circuit assembly having a laminate made of a plurality of substrates is described in a document disclosed in Rao R. Tummala and Eugene J. Rymaszewski, "Microelectronics Packaging Handbook", 1989, Van Nostrand Reinhold, New York, pp.462-464.
Referring to FIG. 7--7 of the reference, two ceramic substrates are stacked in this technique. These ceramic substrates are connected to each other by soldering pins protruding from a lower surface of an upper substrate to an upper surface of a lower substrate.
This prior art, however, has a problem that is described below.
First, it is hard to check a connection state between the substrates. This is because the connected portion is covered with the upper substrate.
Next, it takes a long time for a design change. This is because it requires a longer time to change a design of the ceramic substrates than that of flexible substrates such as tape automated bonding (TAB) tape. Specifically, it takes a few months for a design change of the ceramic substrates, while it takes a few days for a design change of the TAB tape. Particularly, it requires a long time to change processes of a mask for an internal circuit or a screen therefor.